18W 4ft LED T8 Tube, 2200Lm, 5000K Clear IP40 UL 2 end power

This 18 Watt LED Tube is brighter than a 40 Watt Fluorescent Tube. The replacement will save you up to 75% in electricity labor and parts as lifespan is over 15 years. This Single end tube will save you money in unnecessary tube replacements. Estimated annual ROI is about 60%..

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Common terms used in lighting, LED Technology and Glossary

For those of you who need to understand this new world of LED lighting, there is some vocabulary you will need to know. We have given you some terminology that will help you understand what its all about.

LED

LED stands for "light emitting diode." A diode is an electrical component with two terminals which conduct the electricity only in one direction. With an electrical current, the diode emits a bright light around the small bulb.

Lumens vs Watts

LEDs that are bright enough to replace incandescents for business that is, producing the same number of lumens as standard 40- or 60-watt bulbs---typically only use 9 to 12 watts. The U.S. Department of Energy advises that business that want to replace a 60-watt bulb should look for an LED that produces close to 800 lumens; for a 40-watt bulb, look for 450 lumens.

Ballast

In a fluorescent lighting system, the ballast regulates the current to the lamps and provides sufficient voltage to start the lamps. Without a ballast to limit its current, a fluorescent lamp connected directly to a high voltage power source would rapidly and uncontrollably increase its current draw. Within a second the lamp would overheat and burn out.

Thee are several types of ballasts,

Instant startAn instant start ballast does not preheat the electrodes, instead using a relatively high voltage (~600 V) to initiate the discharge arc. It is the most energy efficient type, but yields the fewest lamp-start cycles, as material is blasted from the surface of the cold electrodes each time the lamp is turned on. Instant-start ballasts are best suited to applications with long duty cycles, where the lamps are not frequently turned on and off.

Rapid startA rapid start ballast applies voltage and heats the cathodes simultaneously. It provides superior lamp life and more cycle life, but uses slightly more energy as the cathodes in each end of the lamp continue to consume heating power as the lamp operates. A dimming circuit can be used with a dimming ballast, which maintains the heating current while allowing lamp current to be controlled.

Programmed startA programmed-start ballast is a more advanced version of rapid start. This ballast applies power to the filaments first, it allows the cathodes to preheat and then applies voltage to the lamps to strike an arc. Lamp life typically operates up to 100,000 on/off cycles when using programmed start ballasts. Once started, filament voltage is reduced to increase operating efficiency.[5] This ballast gives the best life and most starts from lamps, and so is preferred for applications with very frequent power cycling such as vision examination rooms and restrooms with a motion detector switch.

HybridA hybrid ballast has a magnetic core-and-coil transformer and an electronic switch for the electrode-heating circuit. Like a magnetic ballast, a hybrid unit operates at line power frequency—60 Hz in North America, for example. These types of ballasts, which are also referred to as “cathode-disconnect ballasts”, disconnect the electrode-heating circuit after they start the lamps.

HID/HPS

High Intensity Discharge bulb. These include the Metal Halide (MH) and High Presure Sodium (HPS) among other types of bulbs that use a mixture of gases that when electrically excited produce an arc that emmits light.

The color of the light depends on the gases used in the arc tube.

UL

Underwriters Laboratory is the certification which indicates that a product meets certain standards that conform with insurance company requirements for safety. An LED bulb without this designation is not of high enough quality for insurance purposes and usually indicates an inferior product.

Kwh

Kilowatt per hour is how you are billed by your electric company. There is a cost per Kwh on your electric bill.

In a fluorescent lighting system or HID bulbs, the ballast regulates the current to the lamps and provides sufficient voltage to start the lamps. Without a ballast to limit its current, a fluorescent lamp connected directly to a high voltage power source would rapidly and uncontrollably increase its current draw. Within a second the lamp would overheat and burn out.

Bin (Binning)

LED manufacturers sort their products into bins based on lumen output and color. Fixture manufacturers specify a range of bins from which they will accept LEDs. If they only accept fixtures from bins that are very close together, the diodes are more expensive, but result in a higher quality fixture. If fixtures are built with LEDs from a wider range of bins, cost and lead-time are reduced. Manufacturers may refer to their “tightly binned” products when they want to convey that theirs is a good quality product.

Black Body / Black Body Radiator

An object that absorbs all electromagnetic radiation falling on it. Because it reflects no light, a black body appears black. As a black body is heated to incandescence, it radiates light in a sequence of colors, from red to orange to yellow to white to blue, depending on its temperature. This color sequence describes a curve within a color space, known as the black-body curve.

Black Body Curve

A curve within a color space describing the sequence of colors emitted by a black-body radiator at different temperatures.

Brightness

Often used incorrectly with respect to illumination as a synonym for luminous flux, an objective measurement of the visible power of a light source. The term is correctly used when describing screen brightness in a display or television. (see Nits).

An objective specification of the quality of a color, independent of its luminance, and as determined by its or saturation and hue.

Color Definition

The color of uniformly illuminated objects described using three terms:

Hue: Describes the situation when the appearance of different colors is similar (e.g. matching blues and pinks).

Lightness: Describes a range of grayness between black and white.

Chroma: Describes the degree of departure from gray of the same lightness and increasing color (e.g. red, redder, pure red).

Color Gamut

The range of colors within the CIE Chromaticity Diagram included when combining different sources.

Color Model

An abstract mathematical model describing the way colors can be represented as groups of values or color components. RGB (Red-Green-Blue) is a color model with three color components, and CMYK (Cyan-Magenta-Yellow and Key (Black)) is a color model with four color components.

Color Rendering

A general expression for the effect of a light source on the color appearance of objects.

Color Rendering Index (CRI)

A measure of the degree of color shift objects undergo when illuminated by the light source as compared with those same objects when illuminated by a reference source of comparable color temperature. The reference source has a CRI of 100.

Color Spectrum / Visible Spectrum

The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye, typically between 390nm and 750nm.

Color temperature

The description used to describe the effect of heating an object until it glows incandescently, the emitted radiation, and apparent color, changes proportional to the temperature; easily envisioned when considering hot metal in a forge that glows red, then orange, and then white as the temperature increases.

Conformal Phosphor Coating

Phosphor application process that uniformly coats the LED chip with phosphor.

Controller

A device that controls the output of color-changing and tunable white lighting fixtures. Controllers typically have software components for configuring fixtures and designing and editing light shows, and hardware components for sending control data to fixtures.

Cool White

A description of a range of correlated color temperatures.

Correlated Color Temperature (CCT)

The absolute temperature of a blackbody whose chromaticity most nearly resembles that of the light source. Usually specified in Kelvin (K). The lower the Kelvin temperature, the warmer the light feels, or appears.

The amount of light a lighting fixture or lighting installation delivers to a target area or task surface, measured in footcandles (fc) or lux (lx).

Diffuser

An object with irregularities on a surface causing scattered reflections.

Direct-View Lighting Fixtures

Lighting fixtures intended for viewing, rather than for illumination. For example, arrays of direct-view fixtures or nodes are used in large-scale video displays, traffic signals, and signage applications.

Directional Light Source

A light source that emits light only in the direction it is pointed or oriented.

Driver

All LED fixtures include an LED driver or power supply. This driver can be integral to the fixture, separate from the fixture or remotely located. Typically, the driver is an important part of every LED system and you should remember it is a factor when using LED fixtures.

The light output of a light source divided by the total electrical power input to that source, expressed in lumens per watt (lm/W).

Efficiency

The percentage of total lamp lumens that a lighting fixture, luminaire, or system emits, minus any blocked or wasted light. See Luminous efficiency.

Epoxy

Organic polymer frequently used for a dome or lens, often prone to optical decay over time, resulting in poor lumen maintenance. High quality LEDs such as LUXEON contain no epoxy in the optical system and deliver superior lumen maintenance.

Eye-sensitivity Curve

A bell-shaped curve describing the sensitivity of a human eye with normal vision to the spectrum of visible light. Also known as the eye-sensitivity curve. See spectral luminous efficiency function.

Luminous flux is the measure of the perceived power of light, adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light

Foot-Candle (Fc)

The unit is defined as the amount of illumination the inside surface of a one-foot-radius sphere would be receiving if there were a uniform point source of one candela in the exact center of the sphere. Alternatively, it can be defined as the illuminance on a one-square foot surface of which there is a uniformly distributed flux of one lumen.

Forward voltage

LEDs are current driven devices. If an external current is passed through the device, a forward voltage will be developed across the diode.

A part of the thermal system that conducts or convects heat away from sensitive components, such as LEDs and electronics.

HID

High Intensity Discharge, usually referred to bulbs that use compressed gass and when voltage is applied creates a high intensity discharge or voltaic arch like in a lighting bolt and thus emmit light.

High Power LED

A high power LED, sometimes referred to as a power LED, is one that is driven at a current of 350 mA or higher.

High-brightness

High-brightness is a term that is often applied to an LED but has no measured meaning and does not indicate any level of performance.

Hot / Cold Factor

The relative light output performance at a temperature compared to the light output at a nominal or test temperature. For LUXEON products this is the relative light output at 100C Tj compared to 25C Tj. For “Hot Tested” products like LUXEON A it is the relative light output at 100C Tj compared to 85C Tj.

HPS

High Preasured Sodium, referred to bulbs that use sodium as presurized gass to produce the high intensity discharge.

Hot Testing

LED performance testing and specification at an elevated temperature of 85°C.

The intensity of light falling on a surface area. If the area is measured in square feet, the unit of illuminance is footcandles (fc). If measured in square meters, the unit of illuminance is lux (lx).

Illuminating Engineering Society of North America (IES)

The recognized technical authority on illumination, communicating information on all aspects of good lighting practice to its members, to the lighting community, and to consumers through a variety of programs, publications, and services.

Inboard Power Integration

An approach to power management that integrates the power supply directly into a fixture’s circuitry, creating an efficient power stage that consolidates line voltage conversion and LED current regulation.

Term and symbol (K) used to indicate the comparative color appearance of a light source when compared to a theoretical blackbody. Yellowish incandescent lamps are 3000K. Fluorescent light sources range from 3000K to 7500K and higher.

Kelvin Temperature

Term and symbol (K) used to indicate the comparative color appearance of a light source when compared to a theoretical blackbody. Yellowish incandescent lamps are 3000K. Fluorescent light sources range from 3000K to 7500K and higher.

LEDA Light Emitting Diode (LED) is a solid-state semiconductor device that converts electrical energy directly into light. On its most basic level, the semiconductor is comprised of two regions. The p-region contains positive electrical charges while the n-region contains negative electrical charges. When voltage is applied and current begins to flow, the electrons move across the n region into the p region. The process of an electron moving through the p-n junction releases energy. The dispersion of this energy produces photons with visible wavelengths.

LED Array

An assembly of LED packages or dies on a printed circuit board or substrate, possibly with optical elements and additional thermal, mechanical, and electrical interfaces that are intended to connect to the load side of an LED driver.

LED Chip (Chip)

The light producing semiconductor device that may or may not be incorporated into an LED.

LED Driver

An electronic circuit that converts input power into a current source — a source in which current remains constant despite fluctuations in voltage. An LED driver protects LEDs from normal voltage fluctuations, overvoltages, and voltage spikes.

LED Light Engine

An integrated assembly comprised of LEDs or LED arrays, LED driver, and other optical, thermal, mechanical, and electrical components.

LED Luminaire

A complete lighting unit consisting of LED-based light emitting elements and a matched driver together with parts to distribut light, to position and protect the light emitting elements, and to connect the unit to a branch circuit. The LED based light emitting elements may take the form of LED packages, (components), LED arrays (modules) LED Light Engine, or LED lamps. The LED luminaire is intended to connect directly to a branch circuit.

Light Emitting Diode (LED)

A Light Emitting Diode (LED) is a solid-state semiconductor device that converts electrical energy directly into light. On its most basic level, the semiconductor is comprised of two regions. The p-region contains positive electrical charges while the n-region contains negative electrical charges. When voltage is applied and current begins to flow, the electrons move across the n region into the p region. The process of an electron moving through the p-n junction releases energy. The dispersion of this energy produces photons with visible wavelengths.

L70

L70 describes the brightness of an LED after a number of hours – often 50,000. If a product claims L70 after 50,000 hours, it means that after 50,000 hours of burning (nearly six years if the lights are on 24/7) the lights are now 70% as bright as they were when they were first installed. L70 doesn’t mean anything without the corresponding number of hours. You may also see terms such as L70 at 6,000 hours. Sometimes manufacturers will list L80 (or even L90) at 50,000 hours. This simply means that after 50,000 hours, the LEDs will be 80% (or 90%) as bright as they were initially. Be careful not to confuse L70 with LM79 or LM80.

This IES document applies to LED fixtures (but not to components.) It prescribes the approved method for “Electrical and Photometric Measurements of Solid-State Lighting Products.” In the beginning, LED products were the wild, wild west. Manufacturers claimed just about anything based on their own personal “test procedures.” LM79 gave structure to the chaos and today LM79 compliance can help ensure that you are comparing apples to apples when you read LED product literature.

This IES (Illuminating Engineering Society of North America)document describes the approved method for “Measuring Lumen Maintenance of LED Light Sources.” It applies to bare LED light sources and does not cover complete luminaires (fixtures.) The main story here is usable life. LED sources, like the old metal halide lamps, tend to fade over life instead of “burning out.” Again, when manufacturers are using the same test methodology, you can be comfortable when comparing products.

Lumen (lm)

The international (SI) unit of luminous flux or quantity of light and equals the amount of light that is spread over a square foot of surface by one candle power when all parts of the surface are exactly one foot from the light source. For example, a dinner candle provides about 12 lumens

Lumen Depreciation

Describes the percentage of light lost relative to the initial lumen output. See lumen maintenance for more information.

Lumen Maintenance

The luminous flux at a give time in the life of the LED. This is expressed as a percentage of the intial luminous flux.

Lumen Maintenance Curve

A graph illustrating the predicted average light output behavior over time of a single LED or solution.

Lumen Output

The total lumens emitted of a light source, system, or solution.

Luminaire

A lighting fixture complete with installed lamps and other accessories.

Luminous Efficiency

The percentage of total lamp lumens that a lighting fixture, luminaire, or system emits, minus any blocked or wasted light.

Luminous Flux

Luminous flux is the measure of the perceived power of light, adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light

Lux (lx)

The SI (International) unit of illuminance, or luminous flux incident on a unit area, frequently defined as one lumen per square meter (lm/m2).

An approach to power management that integrates the power supply into a fixture’s housing, eliminating the need for an external power supply.

Organic Light-emitting Diodes (OLED)

Organic light-emitting diodes (OLEDs) are based on organic (carbon based) materials. In contrast to LEDs, which are small point sources, OLEDs are made in sheets which provide a diffuse area light source. OLED technology is developing rapidly and is increasingly used in display applications such as cell phones and PDA screens. However, OLEDs are still some years away from becoming a practical general illumination source. Additional advancements are needed in light output, color, efficiency, cost, and lifetime.

The active power divided by the apparent power (i.e., product of the rms input voltage and rms input current of a driver).

Power Factor Correction

In an electronic device, such as an LED lighting fixture, a system of inductors, capacitors, or voltage converters to adjust the power factor of electronic devices toward the ideal power factor of 1.0.

Pulse Width Modulation (PWM)

A method, used by LED drivers, to regulate the amount of energy to the LEDs. PWM turns LEDs on and off at high frequency, reducing total ON time to achieve a desired dimming level.

Controlling the operating temperature of the product through design, examples includes heat sinks and improved airflow.

Thermal Pad Temperature

The measured temperature of the thermal pad during tesing. The thermal pad aides in the conduction of heat away from the component being cooled and into the heatsink. For more information refer to LUXEON® Rebel and LUXEON® Rebel ES Assemby and Handling Guide application brief 32.

Thermal Resistance (K/W)

The property of a material's ability to conduct heat.

Tj

Junction Temperature

Tp

Thermal Pad Temperature

Tunable White Light

White-light LED fixtures that combine channels of warm white and cool white LEDs to produce a range of color temperatures.

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Common terms used in lighting, LED Technology and Glossary

For those of you who need to understand this new world of LED lighting, there is some vocabulary you will need to know. We have given you some terminology that will help you understand what its all about.

LED

LED stands for "light emitting diode." A diode is an electrical component with two terminals which conduct the electricity only in one direction. With an electrical current, the diode emits a bright light around the small bulb.

Lumens vs Watts

LEDs that are bright enough to replace incandescents for business that is, producing the same number of lumens as standard 40- or 60-watt bulbs---typically only use 9 to 12 watts. The U.S. Department of Energy advises that business that want to replace a 60-watt bulb should look for an LED that produces close to 800 lumens; for a 40-watt bulb, look for 450 lumens.

Ballast

In a fluorescent lighting system, the ballast regulates the current to the lamps and provides sufficient voltage to start the lamps. Without a ballast to limit its current, a fluorescent lamp connected directly to a high voltage power source would rapidly and uncontrollably increase its current draw. Within a second the lamp would overheat and burn out.

Thee are several types of ballasts,

Instant startAn instant start ballast does not preheat the electrodes, instead using a relatively high voltage (~600 V) to initiate the discharge arc. It is the most energy efficient type, but yields the fewest lamp-start cycles, as material is blasted from the surface of the cold electrodes each time the lamp is turned on. Instant-start ballasts are best suited to applications with long duty cycles, where the lamps are not frequently turned on and off.

Rapid startA rapid start ballast applies voltage and heats the cathodes simultaneously. It provides superior lamp life and more cycle life, but uses slightly more energy as the cathodes in each end of the lamp continue to consume heating power as the lamp operates. A dimming circuit can be used with a dimming ballast, which maintains the heating current while allowing lamp current to be controlled.

Programmed startA programmed-start ballast is a more advanced version of rapid start. This ballast applies power to the filaments first, it allows the cathodes to preheat and then applies voltage to the lamps to strike an arc. Lamp life typically operates up to 100,000 on/off cycles when using programmed start ballasts. Once started, filament voltage is reduced to increase operating efficiency.[5] This ballast gives the best life and most starts from lamps, and so is preferred for applications with very frequent power cycling such as vision examination rooms and restrooms with a motion detector switch.

HybridA hybrid ballast has a magnetic core-and-coil transformer and an electronic switch for the electrode-heating circuit. Like a magnetic ballast, a hybrid unit operates at line power frequency—60 Hz in North America, for example. These types of ballasts, which are also referred to as “cathode-disconnect ballasts”, disconnect the electrode-heating circuit after they start the lamps.

HID/HPS

High Intensity Discharge bulb. These include the Metal Halide (MH) and High Presure Sodium (HPS) among other types of bulbs that use a mixture of gases that when electrically excited produce an arc that emmits light.

The color of the light depends on the gases used in the arc tube.

UL

Underwriters Laboratory is the certification which indicates that a product meets certain standards that conform with insurance company requirements for safety. An LED bulb without this designation is not of high enough quality for insurance purposes and usually indicates an inferior product.

Kwh

Kilowatt per hour is how you are billed by your electric company. There is a cost per Kwh on your electric bill.

In a fluorescent lighting system or HID bulbs, the ballast regulates the current to the lamps and provides sufficient voltage to start the lamps. Without a ballast to limit its current, a fluorescent lamp connected directly to a high voltage power source would rapidly and uncontrollably increase its current draw. Within a second the lamp would overheat and burn out.

Bin (Binning)

LED manufacturers sort their products into bins based on lumen output and color. Fixture manufacturers specify a range of bins from which they will accept LEDs. If they only accept fixtures from bins that are very close together, the diodes are more expensive, but result in a higher quality fixture. If fixtures are built with LEDs from a wider range of bins, cost and lead-time are reduced. Manufacturers may refer to their “tightly binned” products when they want to convey that theirs is a good quality product.

Black Body / Black Body Radiator

An object that absorbs all electromagnetic radiation falling on it. Because it reflects no light, a black body appears black. As a black body is heated to incandescence, it radiates light in a sequence of colors, from red to orange to yellow to white to blue, depending on its temperature. This color sequence describes a curve within a color space, known as the black-body curve.

Black Body Curve

A curve within a color space describing the sequence of colors emitted by a black-body radiator at different temperatures.

Brightness

Often used incorrectly with respect to illumination as a synonym for luminous flux, an objective measurement of the visible power of a light source. The term is correctly used when describing screen brightness in a display or television. (see Nits).

An objective specification of the quality of a color, independent of its luminance, and as determined by its or saturation and hue.

Color Definition

The color of uniformly illuminated objects described using three terms:

Hue: Describes the situation when the appearance of different colors is similar (e.g. matching blues and pinks).

Lightness: Describes a range of grayness between black and white.

Chroma: Describes the degree of departure from gray of the same lightness and increasing color (e.g. red, redder, pure red).

Color Gamut

The range of colors within the CIE Chromaticity Diagram included when combining different sources.

Color Model

An abstract mathematical model describing the way colors can be represented as groups of values or color components. RGB (Red-Green-Blue) is a color model with three color components, and CMYK (Cyan-Magenta-Yellow and Key (Black)) is a color model with four color components.

Color Rendering

A general expression for the effect of a light source on the color appearance of objects.

Color Rendering Index (CRI)

A measure of the degree of color shift objects undergo when illuminated by the light source as compared with those same objects when illuminated by a reference source of comparable color temperature. The reference source has a CRI of 100.

Color Spectrum / Visible Spectrum

The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye, typically between 390nm and 750nm.

Color temperature

The description used to describe the effect of heating an object until it glows incandescently, the emitted radiation, and apparent color, changes proportional to the temperature; easily envisioned when considering hot metal in a forge that glows red, then orange, and then white as the temperature increases.

Conformal Phosphor Coating

Phosphor application process that uniformly coats the LED chip with phosphor.

Controller

A device that controls the output of color-changing and tunable white lighting fixtures. Controllers typically have software components for configuring fixtures and designing and editing light shows, and hardware components for sending control data to fixtures.

Cool White

A description of a range of correlated color temperatures.

Correlated Color Temperature (CCT)

The absolute temperature of a blackbody whose chromaticity most nearly resembles that of the light source. Usually specified in Kelvin (K). The lower the Kelvin temperature, the warmer the light feels, or appears.

The amount of light a lighting fixture or lighting installation delivers to a target area or task surface, measured in footcandles (fc) or lux (lx).

Diffuser

An object with irregularities on a surface causing scattered reflections.

Direct-View Lighting Fixtures

Lighting fixtures intended for viewing, rather than for illumination. For example, arrays of direct-view fixtures or nodes are used in large-scale video displays, traffic signals, and signage applications.

Directional Light Source

A light source that emits light only in the direction it is pointed or oriented.

Driver

All LED fixtures include an LED driver or power supply. This driver can be integral to the fixture, separate from the fixture or remotely located. Typically, the driver is an important part of every LED system and you should remember it is a factor when using LED fixtures.

The light output of a light source divided by the total electrical power input to that source, expressed in lumens per watt (lm/W).

Efficiency

The percentage of total lamp lumens that a lighting fixture, luminaire, or system emits, minus any blocked or wasted light. See Luminous efficiency.

Epoxy

Organic polymer frequently used for a dome or lens, often prone to optical decay over time, resulting in poor lumen maintenance. High quality LEDs such as LUXEON contain no epoxy in the optical system and deliver superior lumen maintenance.

Eye-sensitivity Curve

A bell-shaped curve describing the sensitivity of a human eye with normal vision to the spectrum of visible light. Also known as the eye-sensitivity curve. See spectral luminous efficiency function.

Luminous flux is the measure of the perceived power of light, adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light

Foot-Candle (Fc)

The unit is defined as the amount of illumination the inside surface of a one-foot-radius sphere would be receiving if there were a uniform point source of one candela in the exact center of the sphere. Alternatively, it can be defined as the illuminance on a one-square foot surface of which there is a uniformly distributed flux of one lumen.

Forward voltage

LEDs are current driven devices. If an external current is passed through the device, a forward voltage will be developed across the diode.

A part of the thermal system that conducts or convects heat away from sensitive components, such as LEDs and electronics.

HID

High Intensity Discharge, usually referred to bulbs that use compressed gass and when voltage is applied creates a high intensity discharge or voltaic arch like in a lighting bolt and thus emmit light.

High Power LED

A high power LED, sometimes referred to as a power LED, is one that is driven at a current of 350 mA or higher.

High-brightness

High-brightness is a term that is often applied to an LED but has no measured meaning and does not indicate any level of performance.

Hot / Cold Factor

The relative light output performance at a temperature compared to the light output at a nominal or test temperature. For LUXEON products this is the relative light output at 100C Tj compared to 25C Tj. For “Hot Tested” products like LUXEON A it is the relative light output at 100C Tj compared to 85C Tj.

HPS

High Preasured Sodium, referred to bulbs that use sodium as presurized gass to produce the high intensity discharge.

Hot Testing

LED performance testing and specification at an elevated temperature of 85°C.

The intensity of light falling on a surface area. If the area is measured in square feet, the unit of illuminance is footcandles (fc). If measured in square meters, the unit of illuminance is lux (lx).

Illuminating Engineering Society of North America (IES)

The recognized technical authority on illumination, communicating information on all aspects of good lighting practice to its members, to the lighting community, and to consumers through a variety of programs, publications, and services.

Inboard Power Integration

An approach to power management that integrates the power supply directly into a fixture’s circuitry, creating an efficient power stage that consolidates line voltage conversion and LED current regulation.

Term and symbol (K) used to indicate the comparative color appearance of a light source when compared to a theoretical blackbody. Yellowish incandescent lamps are 3000K. Fluorescent light sources range from 3000K to 7500K and higher.

Kelvin Temperature

Term and symbol (K) used to indicate the comparative color appearance of a light source when compared to a theoretical blackbody. Yellowish incandescent lamps are 3000K. Fluorescent light sources range from 3000K to 7500K and higher.

LEDA Light Emitting Diode (LED) is a solid-state semiconductor device that converts electrical energy directly into light. On its most basic level, the semiconductor is comprised of two regions. The p-region contains positive electrical charges while the n-region contains negative electrical charges. When voltage is applied and current begins to flow, the electrons move across the n region into the p region. The process of an electron moving through the p-n junction releases energy. The dispersion of this energy produces photons with visible wavelengths.

LED Array

An assembly of LED packages or dies on a printed circuit board or substrate, possibly with optical elements and additional thermal, mechanical, and electrical interfaces that are intended to connect to the load side of an LED driver.

LED Chip (Chip)

The light producing semiconductor device that may or may not be incorporated into an LED.

LED Driver

An electronic circuit that converts input power into a current source — a source in which current remains constant despite fluctuations in voltage. An LED driver protects LEDs from normal voltage fluctuations, overvoltages, and voltage spikes.

LED Light Engine

An integrated assembly comprised of LEDs or LED arrays, LED driver, and other optical, thermal, mechanical, and electrical components.

LED Luminaire

A complete lighting unit consisting of LED-based light emitting elements and a matched driver together with parts to distribut light, to position and protect the light emitting elements, and to connect the unit to a branch circuit. The LED based light emitting elements may take the form of LED packages, (components), LED arrays (modules) LED Light Engine, or LED lamps. The LED luminaire is intended to connect directly to a branch circuit.

Light Emitting Diode (LED)

A Light Emitting Diode (LED) is a solid-state semiconductor device that converts electrical energy directly into light. On its most basic level, the semiconductor is comprised of two regions. The p-region contains positive electrical charges while the n-region contains negative electrical charges. When voltage is applied and current begins to flow, the electrons move across the n region into the p region. The process of an electron moving through the p-n junction releases energy. The dispersion of this energy produces photons with visible wavelengths.

L70

L70 describes the brightness of an LED after a number of hours – often 50,000. If a product claims L70 after 50,000 hours, it means that after 50,000 hours of burning (nearly six years if the lights are on 24/7) the lights are now 70% as bright as they were when they were first installed. L70 doesn’t mean anything without the corresponding number of hours. You may also see terms such as L70 at 6,000 hours. Sometimes manufacturers will list L80 (or even L90) at 50,000 hours. This simply means that after 50,000 hours, the LEDs will be 80% (or 90%) as bright as they were initially. Be careful not to confuse L70 with LM79 or LM80.

This IES document applies to LED fixtures (but not to components.) It prescribes the approved method for “Electrical and Photometric Measurements of Solid-State Lighting Products.” In the beginning, LED products were the wild, wild west. Manufacturers claimed just about anything based on their own personal “test procedures.” LM79 gave structure to the chaos and today LM79 compliance can help ensure that you are comparing apples to apples when you read LED product literature.

This IES (Illuminating Engineering Society of North America)document describes the approved method for “Measuring Lumen Maintenance of LED Light Sources.” It applies to bare LED light sources and does not cover complete luminaires (fixtures.) The main story here is usable life. LED sources, like the old metal halide lamps, tend to fade over life instead of “burning out.” Again, when manufacturers are using the same test methodology, you can be comfortable when comparing products.

Lumen (lm)

The international (SI) unit of luminous flux or quantity of light and equals the amount of light that is spread over a square foot of surface by one candle power when all parts of the surface are exactly one foot from the light source. For example, a dinner candle provides about 12 lumens

Lumen Depreciation

Describes the percentage of light lost relative to the initial lumen output. See lumen maintenance for more information.

Lumen Maintenance

The luminous flux at a give time in the life of the LED. This is expressed as a percentage of the intial luminous flux.

Lumen Maintenance Curve

A graph illustrating the predicted average light output behavior over time of a single LED or solution.

Lumen Output

The total lumens emitted of a light source, system, or solution.

Luminaire

A lighting fixture complete with installed lamps and other accessories.

Luminous Efficiency

The percentage of total lamp lumens that a lighting fixture, luminaire, or system emits, minus any blocked or wasted light.

Luminous Flux

Luminous flux is the measure of the perceived power of light, adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light

Lux (lx)

The SI (International) unit of illuminance, or luminous flux incident on a unit area, frequently defined as one lumen per square meter (lm/m2).

An approach to power management that integrates the power supply into a fixture’s housing, eliminating the need for an external power supply.

Organic Light-emitting Diodes (OLED)

Organic light-emitting diodes (OLEDs) are based on organic (carbon based) materials. In contrast to LEDs, which are small point sources, OLEDs are made in sheets which provide a diffuse area light source. OLED technology is developing rapidly and is increasingly used in display applications such as cell phones and PDA screens. However, OLEDs are still some years away from becoming a practical general illumination source. Additional advancements are needed in light output, color, efficiency, cost, and lifetime.

The active power divided by the apparent power (i.e., product of the rms input voltage and rms input current of a driver).

Power Factor Correction

In an electronic device, such as an LED lighting fixture, a system of inductors, capacitors, or voltage converters to adjust the power factor of electronic devices toward the ideal power factor of 1.0.

Pulse Width Modulation (PWM)

A method, used by LED drivers, to regulate the amount of energy to the LEDs. PWM turns LEDs on and off at high frequency, reducing total ON time to achieve a desired dimming level.

Controlling the operating temperature of the product through design, examples includes heat sinks and improved airflow.

Thermal Pad Temperature

The measured temperature of the thermal pad during tesing. The thermal pad aides in the conduction of heat away from the component being cooled and into the heatsink. For more information refer to LUXEON® Rebel and LUXEON® Rebel ES Assemby and Handling Guide application brief 32.

Thermal Resistance (K/W)

The property of a material's ability to conduct heat.

Tj

Junction Temperature

Tp

Thermal Pad Temperature

Tunable White Light

White-light LED fixtures that combine channels of warm white and cool white LEDs to produce a range of color temperatures.